This disclosure relates to devices and methods for holding together two or more wires, wire harnesses, cables or other objects, or for connecting such objects to other structures. More particularly, the disclosure relates to cable lacing tie assemblies for use in bundling a plurality of objects such as wires, wire harnesses, cables or other objects, and methods of using such cable lacing tie assemblies.
Individual wires, wire harnesses or cables having two or more wires or strands are customarily grouped and held adjacent to each other at various points along their lengths by use of cable ties or cable lacing tape. Strapping or tying together such groupings is intended to help ensure the safety and durability of the components.
Cable ties have become very common and typically are formed from an integrally molded piece of plastic that includes an elongated solid strap connected at one end to a buckle. The strap is intended to be looped around a bundle of wires and then fed through a passageway in the buckle. Corresponding surfaces on the strap and within the buckle commonly have complementary serrated patterns that can achieve a locking position. Thus, a cable tie buckle often includes an integrally molded locking element or pawl within the passageway to cooperate with integrally molded serrations or teeth along the strap. The buckle may include a separately provided metal pawl to engage the serrations on the strap. Alternatively, the strap may have flat surfaces and the buckle may include a separately provided metal barb or knife-like strap piercing element to cut or bite into the strap and prevent rearward withdrawal of the strap. However, such a barb or knife like strap piercing element is destructive to the strap when it cuts or bites into the strap, permanently reducing the strength of the strap and increasing the tendency for the strap to tear through.
Once a strap of a cable tie is passed through the buckle, it may be cut to remove the free end. However, the cut section of the molded plastic strap that protrudes from the buckle can present an undesirable, fairly sharp obstruction that may result in abrasion problems with respect to adjacent wire bundles, and may be problematic if one is attempting to pull the wire bundle through an aperture, such as a panel opening. This also can be true of the molded buckle itself, which can be relatively large and may have fairly sharp edges. It should be noted that another drawback of molded plastic cable ties is that, due to their relative rigidity, they generally are not capable of closely hugging irregular or rectangular shapes, as may occur when bundling wires, wire harnesses or cables, or connecting them to other structures.
In the aerospace environment, a cable tie can be subjected to elevated temperatures as high as 400 degrees F. This can cause a common cable tie, which is typically molded from thermoplastic material, such as Nylon, to creep or lose structural integrity. The integral locking element or pawl that engages the strap then may yield, allowing the wire bundle to separate or come loose. The locking element or pawl generally will be constructed to be deflectable, so as to reduce the strap insertion force, but this also compromises the ability to retain the strap, especially at high temperatures. Cable ties that have a separately provided metal locking element or pawl usually are intended to provide for increased retention, even at elevated temperatures, but these structures typically require higher insertion forces when passing over the metal element.
Because of many of the above drawbacks associated with plastic molded cable ties, in areas where elevated levels of safety are required, such as in the military and commercial aircraft industries, the aerospace industry, as well as in some marine environments, there is a preference to use a procedure known as “cable lacing” for securing or bundling wires, wiring harnesses or cables. Cable lacing includes looping a material commonly referred to as “cable lacing tape” around wires, wire harnesses or cables and tying knots in the cable lacing tape, either in discrete locations along the length of the bundle, referred to as spot ties, or in a running format with the cable lacing tape continuing along the bundle between knot locations.
Modern cable lacing tapes typically are a thin, relatively flat, woven or braided cord, often referred to as a “tape”, having filaments that may be made of materials such as Nylon, polyester or Nomex, and which may be impregnated with coatings to enhance particular performance characteristics. Materials such as Nomex provide good tensile strength, while being non-flammable, highly resistant to fluids and lubricants, and able to perform in extreme temperature environments, such as from approximately −65 degrees F. to 500 degrees F. However, cable lacing has drawbacks in that the cable lacing tape typically is tied by hand in a costly, labor-intensive, and time-consuming process. Due to these problems, several attempts have been made to automate the cable lacing process. One such device for automated knot tying is described in U.S. Pat. No. 6,648,378.
Such knot tying devices have their own drawbacks and one still is faced with using cable lacing tape that must be cut. Indeed, after forming a spot tie, it is common to cut the ends of the cable lacing tape, so as not to leave them hanging or susceptible to being snagged by other objects. However, cutting the ends of the cable lacing tape may lead to the unraveling of the braided filaments. Therefore, in some installations, it has become common to attempt to fuse the filaments of a cut cable lacing tape end by applying a binding agent, such as a drop of adhesive or glue. The need to incorporate the use of adhesives or glues into the assembly method may present additional difficulties, such as for example cleanliness of the application, unintentional bonding of other objects or surfaces, and the introduction of potentially undesirable fumes, and/or flammable or incompatible fluids or materials.